1. Field of the Invention
The present invention relates to an electric generation control device of an electric generator for use in movable bodies such as an automotive vehicle, an electric vehicle, a marine vessel, portable power generators, small-sized generators for home use, and other mobile devices.
2. Description of the Related Art
As shown in FIG. 13, there is a conventional electric generation control device of an electric generator for use in a vehicle. The conventional electric generation control device has a chopper circuit and an exciting control circuit. The chopper circuit is composed of a power transistor 11 as a switching transistor placed between an electric generator and a battery 9. The exciting control circuit has a field winding 4 and a bypass diode 12 which are connected in parallel. Because such types of exciting control devices, having the configuration shown in FIG. 13 cannot regenerate the field magnetic energy to the battery 9, the field magnetic energy flows through the bypass diode 12 and this involves a drawback to cause late demagnetization.
In order to solve this drawback, there is a related-art technique disclosed in a Japanese patent publication number JP-S62-203599 that shows an exciting control device as shown in FIG. 14. The exciting control device shown in FIG. 14 has a bridge circuit composed of a pair of arms made of power transistors 13 and 14 and another pair of arms made of power transistors 15 and 16. This configuration shown in FIG. 14 can achieve the regeneration of the field magnetic energy in which the field magnetic energy generated in the field winding 4 can be regenerated to the battery 9.
However, the configuration of the above related art involves a drawback. For example, the configuration shown in FIG. 14 needs a large number of configuration elements that form the exciting control circuit when compared with that of the configuration shown in FIG. 13 and thereby decreases the reliability of each element forming the exciting control circuit.
In a concrete example, when each element has a same reliability (reliability f=95%), because the configuration shown in FIG. 13 involves the two elements, the entire reliability of the exciting control circuit becomes 0.9025 (because of f2=0.95×0.95=0.9025). On the contrary, because the configuration shown in FIG. 14 involves the four elements, the entire reliability of the exciting control circuit becomes 0.8145 (because of f4=0.95×0.95×0.95×0.95=0.8145). Thus, because of having a low reliability, the exciting control device shown in FIG. 14 is not very useful at present.